Hough L E, Spannuth M, Nakata M, Coleman D A, Jones C D, Dantlgraber G, Tschierske C, Watanabe J, Körblova E, Walba D M, Maclennan J E, Glaser M A, Clark N A
Department of Physics and Liquid Crystal Materials Research Center, University of Colorado, Boulder, CO 80309, USA.
Science. 2009 Jul 24;325(5939):452-6. doi: 10.1126/science.1170028.
A variety of simple bent-core molecules exhibit smectic liquid crystal phases of planar fluid layers that are spontaneously both polar and chiral in the absence of crystalline order. We found that because of intralayer structural mismatch, such layers are also only marginally stable against spontaneous saddle splay deformation, which is incompatible with long-range order. This results in macroscopically isotropic fluids that possess only short-range orientational and positional order, in which the only macroscopically broken symmetry is chirality--even though the phases are formed from achiral molecules. Their conglomerate domains exhibit optical rotatory powers comparable to the highest ever found for isotropic fluids of chiral molecules.
多种简单的弯核分子呈现出平面流体层的近晶液晶相，在没有晶体有序性的情况下，这些流体层自发地具有极性和手性。我们发现，由于层内结构不匹配，这样的层对于自发的鞍形展曲变形也只是勉强稳定，而这种变形与长程有序不相容。这导致宏观上各向同性的流体，仅具有短程的取向和位置有序，其中唯一宏观上破缺的对称性是手性——尽管这些相是由非手性分子形成的。它们的聚集体域表现出的旋光能力与手性分子各向同性流体中所发现的最高旋光能力相当。
